1. Field of the Application
The subject application relates to a bladed wheel of an axial turbomachine. More particularly, the subject application relates to the problem of locking or clamping the blades in a circumferential groove of a rotor. More particularly, the subject application relates to a blade clamping lock in such a groove.
2. Description of Related Art
Patent EP 1801355 A1 shows a lock for clamping the blades in a circumferential groove. The problem addressed in this document is the positioning of such a lock, particularly in one or more of the downstream stages of the low-pressure compressor of a jet engine. In fact, due to the inclined slope of this part of the drum's shell, the axis of the screw is generally inclined relative to the mean plane of the lock so as to be generally perpendicular to the axis of rotation of the drum. This consequence of this construction is that the lock can position itself poorly when tightening the screw. The disclosed solution is essentially to provide a rotational support surface about which the lock can be pivoted in a radial plane in order to position itself.
Patent FR 2886336 A1 relates to a blade clamping lock, similar to that in the previous document. It addresses the problem of holding the lock in the recess or circumferential groove of a compressor drum. The lock described therein includes front and rear support surfaces with respective bosses designed to prevent the lock from sliding circumferentially.
Patent GB 639320 discloses a blade clamping lock in a circumferential groove in a compressor rotor. Although the lock has two screws spread across the length of the lock, this document does not seem to address the issue of adjusting the tightening forces on each screw, or the problem of bulkiness.
Patent US 2011/0116933 A1 relates also to clamping blades in a circumferential groove in a compressor drum using locks. The particularity of this interpretation lies in only one of the two lips of the groove having slots. Therefore, the lock has a correspondingly designed shape, namely a rounded shape towards the lip of the groove having slots and a straight shape on the opposite lip.
In some of the interpretations mentioned above, the lock comprises an elongated generally vertical chamber through which there is a hole through which the clamping screw is inserted. The upper edge of this chamber is sized to be aligned with the outer surfaces of adjacent platforms of the blades when the lock is in position. This chamber provides an easy and reliable way of visually checking the correct positioning of the lock while it is being tightened.
Although great strides have been made in the area of drum blade locks, many shortcomings remain.